IBM Personal System/2 65 SX User Manual

Description
Programmable Option Select (POS) eliminates the need for switches
by replacing their function with programmable registers. This section
describes the POS information used specifically by the the Model 65
SX system board. For additional! POS information, refer to the
Hardware Interface Technical Reference Micro Channel architecture
information.
Warning:
IBM recommends that programmable options be set only through
the System-Configuration utilities. Directly setting the POS
registers or CMOS RAM POS parameters can result in multiple
assignments of the same system resource, improper operation of
the feature, loss of data, or damage to the hardware.
Application programs should not use the adapter identification
(ID) unless absolutely necessary. Compatibility problems can
result.
If an adapter and the system board are in setup mode at the same
time, bus contention occurs. When this happens, no useful
programming can take place, and damage to the hardware can
occur.
After setup operations are complete, the Adapter Enable/Setup
register (hex 0096) should be set to hex 00, and the System-Board
Enable/Setup register (nex 0094) should be set to hex FF.
The channel-reset bit (bit 7) in the Adapter Enable/Setup register
(hex 0096) must be set to 0 to program the adapters.
The system board does not support 16-bit I/O operations to 8-bit
POS registers. Using 16-bit I/O instructions on 8-bit POS
registers causes incorrect data to be written to or read from the
registers. The system board supports only 8-bit transfers for
setup operations.
Model 65 POS — October 1990 2-3

IBM Personal System/2 65 SX Specifications

General

Brand	IBM
Model	Personal System/2 65 SX
Category	Desktop
Language	English